In recent years, liquid crystal panels have been widely used as a display portion of television devices, cell phones, and tablet computers. The liquid crystal panels do not emit light, and therefore, light from a lighting unit (a backlight unit) is used. Such kind of lighting units are arranged on a rear surface side of the liquid crystal panel to be configured to emit planar light toward a rear surface of the liquid crystal panel.
An example of the kind that is disclosed in Patent Document 1 includes a light guide plate and LED light sources that are opposite an edge surface of the light guide plate. Such lighting units are known as side-lighting units (or edge light lighting units) and each includes the edge surface of the light guide plate as a light entrance surface and a front side surface of the light guide plate as a light exit surface.
In such a lighting unit, the LED light sources are arranged to have a clearance from the light entrance surface. It is preferable not to have any clearance between the LED light sources and the light entrance surface to obtain good use efficiency (light entrance efficiency) of light emitted by the LED light sources. However, a certain clearance is provided between the LED light sources and the light entrance surface with considering thermal expansion of the light guide plate, a tolerance of each component of the lighting unit, and an erection tolerance of components.
As is described in patent Document 1, the LED light sources are mounted on an LED board and the LED board includes a support member projecting therefrom. The support member is in contact with the light entrance surface to keep a distance (a clearance) between the light entrance surface and the LED light sources.
Patent Document 1: Japanese Unexamined Patent Publication No. 2012-220689